It is important to identify forms of a drug that can be conveniently manufactured, formulated and administered to a patient.
Furthermore, in the manufacture of oral drug compositions, it is important that the drug is in a form that provides reliable and reproducible plasma concentrations following administration to a patient.
Chemical stability, solid state stability and “shelf life” of the drug substance are also a particularly important factors. The drug substance, and compositions containing it, should ideally be capable of being effectively stored over appreciable periods of time, without exhibiting a significant change in the active component's physico-chemical characteristics (e.g. its chemical composition, density, hygroscopicity and solubility).
Moreover, it is also important to be able to provide drug in a form which is as chemically pure as possible.
It is known that amorphous drug materials may present some problems in this regard. For example, such materials are typically difficult to handle and to formulate, provide for unreliable solubility, and are often found to be unstable and chemically impure.
The skilled person will therefore appreciate that, if a drug can be readily obtained in a stable crystalline form, many of the above problems may be solved. Thus, in the manufacture of commercially viable, and pharmaceutically acceptable, drug compositions, it is important, wherever possible, to provide drug in a substantially crystalline and stable form. It is to be noted, however, that this goal is not always achievable. Indeed, based on molecular structure alone, it is not typically possible to predict what the crystallisation behaviour of a compound, either as such or in the form of a salt, will be. This can only be determined empirically.
WO2004/103306, the entire contents of which are incorporated herein by reference, discloses a series of compounds capable of inhibiting EDG receptors. WO2004/103306 teaches that the compounds disclosed therein are potentially useful agents for use in the therapy of a number of medical conditions mediated by lymphocytes, such as, for example, transplant rejection, autoimmune conditions and cancer. A full list of possible conditions is recited at page 13, line 9 to page 14, line 3 of WO2004/103306. One particular compound disclosed in WO2004/103306 is 1-(4-{1-[(E)-4-cyclohexyl-3-trifluoromethyl-benzyloxyimino]-ethyl}-2-ethyl-benzyl)-azetidine-3-carboxylic acid (Compound I), the structure of which is shown below.
However, there is no disclosure in WO2004/103306 of any salt or crystalline forms of Compound I.